Linked Questions

13
votes
1answer
3k views

What are quaternions and how are they used to represent spacecraft dynamics?

The title says it all. Quaternions are widely used to represent the orientation of a spacecraft. Why is that, and how do quaternions compare to other alternatives?
6
votes
2answers
605 views

What determines the orbital speed around a massless Lagrangian point?

What value of M should I use to calculate the speed of a satellite orbiting a Lagrangian point where there exists no mass?
11
votes
1answer
1k views

Are some Halo Orbits actually Stable?

UPDATE: I found another reference! While I always enjoy a good video starring Jimmy and Linda Carter, this one has Dennis Wingo describing ISEE-3's original Halo orbit. He describes Sun-Earth $L_1$ as ...
10
votes
1answer
322 views

What are the practical uses of a state transition matrix?

I am studying different dynamical models of relative motion of satellites. In my work, I've always just used a numerical integrator like RK78 to integrate the cartesian system of equations: $\dot{r}=...
-3
votes
2answers
1k views

What precisely is downrange distance - how is it defined mathematically?

Wikipedia: Downrange is the horizontal distance traveled by a spacecraft, or the spacecraft's horizontal distance from the launch site. Spacecraft don't travel horizontally. I don't even know how ...
10
votes
1answer
1k views

How does QUESS, China's quantum communications satellite experiment, relay entangled signals?

China launched the Quantum Experiments at Space Scale (QUESS) on the satellite called MOZI or Micius today, which will be used for quantum communications between China and Europe. Popular Science ...
4
votes
1answer
613 views

What is the difference between halo orbits and Lissajous orbits?

The Wikipedia articles for halo orbit and Lissajous orbit leave me wondering how these two orbits are different from an orbital mechanical point of view. Could they be discussed together here, so I ...
4
votes
1answer
332 views

'Orbiting' Earth-Moon $L_1$

I'm a Sci-Fi author, trying to keep the physics real in my books. I am in the process of moving a space station to the Earth-Moon $L_1$. I've read that a vessel can't just sit at that point, but has ...
2
votes
2answers
185 views

Could the Lunar Lagrange Points work for space telescopes?

Every orbit in space has its pros and cons. Low Earth Orbit has accessibility but frequent eclipses whereas a Solar Lagrange Point is clear and stable but distant. In the case of the Lunar Lagrange ...
12
votes
1answer
437 views

What sort of orbital elements are used to describe halo orbits?

For standard orbits we can use Keplerian elements, TLE, or other similar. These don't make much sense for Halo orbits, which are not around a central body, but around a Lagrangian point, and follow an ...
2
votes
1answer
541 views

Restricted Three body problem need to create an orbit around the two massive bodies

I have assignment and part of it involves getting a satellite to orbit both the Earth and the Moon at least once. How ever no matter how I set my initial condition or parameterize my position and time ...
0
votes
2answers
157 views

How to prepare for an interview for a Pure Mathematics position at ISRO's Space Application Center?

I have completed a Master's in Pure Mathematics. I have read topics like Abstract Algebra, Linear Algebra, Functional Analysis, Topology, Cryptography, Course in C++, etc. Recently I found an ...
3
votes
1answer
155 views

How to get Ltool by Martin et.al?

I am just starting work on dynamics of CRTBP. Over several papers I see that "Ltool" is used for trajectory design, But I am unable to find over internet. Can somebody help me to identfy how to ...
2
votes
0answers
319 views

How to find Near Rectilinear Halo Orbits (NHROs)?

Looking all the good questions and answers in this site referent to CR3BP dynamics, periodic orbits, state transition matrices, etc. I wonder: what algorithm or steps do I have to follow to find the ...
2
votes
1answer
87 views

Is it obvious or easily-proven that L4 and L5 must be in the parental orbital plane?

Looking at the question and answer and diagrams from Are Lagrangian points associated only with the smaller body? got me wondering. L4 and L5 each form an equilateral triangle with the two main ...

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